Open cell semi-rigid polyurethane foams synthesized using palm oil-based polyol

Abstract

Semi-rigid polyurethane foams were successfully prepared by blending up to 70 wt.% of a palm oil-based bio-polyol with a petrochemical polyether polyol. Due to the high viscosity of the bio-polyol derived from palm oil, polyol premixes were heated before mixing with an isocyanate component. Despite this, a slowdown in the foaming and gelling reactions was detected as the content of the palm oil-based bio-polyol in the formulation increased. The thermal conductivity of the modified foams was higher than that of the reference one, even when they exhibited a lower apparent density. In addition, their mechanical and dynamic mechanical properties decreased as the palm oil-based polyol content in the final foams increased. These effects are attributed to the foams’ cellular structure since the closed cell content decreased as the amount of the petrochemical polyol replaced by the bio-polyol increased. However, the water absorption decreased as the bio-polyol concentration in the polyurethane formulation increased and the modified foams exhibited excellent dimensional stability Taking into account potential applications of polyurethane systems, the formulation containing 30 wt.% of the bio-polyol could be used in the preparation of a new generation open cell semi-rigid foams permeable to moisture and with higher content of biomass-derived constituents.